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Orthodontics Flashcards

7 cards from real DMD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Orthodontics flashcards as text

  1. According to Angle's classification, which occlusal relationship is present when the mesiobuccal cusp of the maxillary first molar occludes in the buccal groove of the mandibular first molar?

    Answer: Class I

    Class I is defined by the mesiobuccal cusp of the upper first molar occluding in the buccal groove of the lower first molar, representing the ideal molar relationship.

  2. Which cephalometric landmark is defined as the most anteroinferior point on the contour of the mandibular symphysis?

    Answer: Gnathion (Gn)

    Gnathion (Gn) is the most anteroinferior point on the mandibular symphysis, located midway between Pogonion and Menton on the bony chin.

  3. Which type of orthodontic force is most effective for producing physiologic tooth movement without causing hyalinization of the periodontal ligament?

    Answer: Light continuous forces within the range of capillary blood pressure

    Light continuous forces (approximately 20–26 g/cm²) maintain capillary blood flow in the PDL, allowing steady osteoblast and osteoclast activity without necrosis or hyalinization.

  4. The 'leeway space' (E-space) in the dental arch refers to the difference in mesiodistal width between which tooth groups?

    Answer: Primary canines/molars and permanent canines/premolars

    Leeway space is the difference between the combined mesiodistal widths of the primary canine, first molar, and second molar versus the permanent canine, first premolar, and second premolar — averaging about 1.5 mm per side in the mandible.

  5. Which orthodontic wire alloy exhibits the highest springback (range of action) and is most commonly used during the initial alignment phase of fixed appliance therapy?

    Answer: Nickel-titanium (NiTi)

    Nickel-titanium (NiTi) wires have the highest springback due to their superelastic or thermoelastic properties, delivering light, continuous forces ideal for initial leveling and alignment.

  6. The Frankfort horizontal plane used in cephalometric analysis is constructed by connecting which two landmarks?

    Answer: Porion and Orbitale

    The Frankfort horizontal plane connects Porion (top of the external auditory meatus) and Orbitale (lowest point of the bony orbit), approximating the natural head position.

  7. In lateral cephalometric analysis, the SNA angle measures the anteroposterior position of which structure relative to the cranial base?

    Answer: Maxilla relative to the cranial base

    The SNA angle measures the anteroposterior position of the maxilla (A point) relative to the cranial base (SN plane); the norm is approximately 82°.